/*
 * Copyright (c) 2005-2006 jME Physics 2
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 *  * Neither the name of 'jME Physics 2' nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.jmex.physics.callback;

import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.concurrent.ConcurrentLinkedQueue;

import com.jme.math.Vector3f;
import com.jmex.physics.DynamicPhysicsNode;
import com.jmex.physics.PhysicsSpace;
import com.jmex.physics.PhysicsUpdateCallback;

/**
 * FrictionCallback provides features to apply friction per step for a DynamicPhysicsNode.
 * This class is thread-safe.
 * 
 * @author Matthew D. Hicks
 */
public class FrictionCallback implements PhysicsUpdateCallback {
	private ConcurrentLinkedQueue<FrictionEncapsulation> nodes;
	
	public FrictionCallback() {
		nodes = new ConcurrentLinkedQueue<FrictionEncapsulation>();
	}
	
	public boolean add(DynamicPhysicsNode node, float forceFriction, float angularFriction) {
		return nodes.add(new FrictionEncapsulation(node, forceFriction, angularFriction));
	}
	
	public void afterStep(PhysicsSpace space, float time) {
		Iterator<FrictionEncapsulation> iterator = nodes.iterator();
		FrictionEncapsulation fe;
		while (iterator.hasNext()) {
			fe = iterator.next();
			if (!fe.call(space, time)) {
				iterator.remove();
			}
		}
	}

	public void beforeStep(PhysicsSpace space, float time) {
	}
}

class FrictionEncapsulation {
	private static Vector3f store = new Vector3f();
	
	private WeakReference<DynamicPhysicsNode> node;
	private float forceFriction;
	private float angularFriction;
	
	public FrictionEncapsulation(DynamicPhysicsNode dpn, float forceFriction, float angularFriction) {
		this.node = new WeakReference<DynamicPhysicsNode>(dpn);
		this.forceFriction = forceFriction;
		this.angularFriction = angularFriction;
	}
	
	public boolean call(PhysicsSpace space, float time) {
		DynamicPhysicsNode dpn = node.get();
		if (dpn == null) return false;
		
		if (forceFriction != 0.0f) {
			dpn.getLinearVelocity(store);
			float change = forceFriction * time;
			applyFriction(change);
			dpn.setLinearVelocity(store);
		}
		if (angularFriction != 0.0f) {
			dpn.getAngularVelocity(store);
			float change = angularFriction * time;
			applyFriction(change);
			dpn.setAngularVelocity(store);
		}
		
		return true;
	}
	
	private void applyFriction(float change) {
		if (store.x > 0.0f) {
			store.x -= change;
			if (store.x < 0.0f) store.x = 0.0f;
		} else if (store.x < 0.0f) {
			store.x = store.x + change;
			if (store.x > 0.0f) store.x = 0.0f;
		}
		if (store.y > 0.0f) {
			store.y = store.y - change;
			if (store.y < 0.0f) store.y = 0.0f;
		} else if (store.y < 0.0f) {
			store.y = store.y + change;
			if (store.y > 0.0f) store.y = 0.0f;
		}
		if (store.z > 0.0f) {
			store.z = store.z - change;
			if (store.z < 0.0f) store.z = 0.0f;
		} else if (store.z < 0.0f) {
			store.z = store.z + change;
			if (store.z > 0.0f) store.z = 0.0f;
		}
	}
}